Merge pull request #263 from kaczmarczyck/large-blobs

Large blobs

libraries/persistent_store/src/fragment.rs

@@ -24,6 +24,7 @@ use alloc::vec::Vec;
 use core::ops::Range;
 
 /// Represents a sequence of keys.
+#[allow(clippy::len_without_is_empty)]
 pub trait Keys {
     /// Returns the number of keys.
     fn len(&self) -> usize;

src/ctap/command.rs

@@ -22,6 +22,7 @@ use super::data_formats::{
 };
 use super::key_material;
 use super::status_code::Ctap2StatusCode;
+use super::storage::MAX_LARGE_BLOB_ARRAY_SIZE;
 use alloc::string::String;
 use alloc::vec::Vec;
 use arrayref::array_ref;
@@ -33,6 +34,9 @@ use core::convert::TryFrom;
 // You might also want to set the max credential size in process_get_info then.
 pub const MAX_CREDENTIAL_COUNT_IN_LIST: Option<usize> = None;
 
+// This constant is a consequence of the structure of messages.
+const MIN_LARGE_BLOB_LEN: usize = 17;
+
 // CTAP specification (version 20190130) section 6.1
 #[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug, PartialEq))]
 pub enum Command {
@@ -44,8 +48,8 @@ pub enum Command {
     AuthenticatorGetNextAssertion,
     AuthenticatorCredentialManagement(AuthenticatorCredentialManagementParameters),
     AuthenticatorSelection,
+    AuthenticatorLargeBlobs(AuthenticatorLargeBlobsParameters),
     AuthenticatorConfig(AuthenticatorConfigParameters),
-    // TODO(kaczmarczyck) implement FIDO 2.1 commands (see below consts)
     // Vendor specific commands
     AuthenticatorVendorConfigure(AuthenticatorVendorConfigureParameters),
 }
@@ -56,8 +60,6 @@ impl From<cbor::reader::DecoderError> for Ctap2StatusCode {
     }
 }
 
-// TODO: Remove this `allow(dead_code)` once the constants are used.
-#[allow(dead_code)]
 impl Command {
     const AUTHENTICATOR_MAKE_CREDENTIAL: u8 = 0x01;
     const AUTHENTICATOR_GET_ASSERTION: u8 = 0x02;
@@ -65,8 +67,8 @@ impl Command {
     const AUTHENTICATOR_CLIENT_PIN: u8 = 0x06;
     const AUTHENTICATOR_RESET: u8 = 0x07;
     const AUTHENTICATOR_GET_NEXT_ASSERTION: u8 = 0x08;
-    // TODO(kaczmarczyck) use or remove those constants
+    // Implement Bio Enrollment when your hardware supports biometrics.
-    const AUTHENTICATOR_BIO_ENROLLMENT: u8 = 0x09;
+    const _AUTHENTICATOR_BIO_ENROLLMENT: u8 = 0x09;
     const AUTHENTICATOR_CREDENTIAL_MANAGEMENT: u8 = 0x0A;
     const AUTHENTICATOR_SELECTION: u8 = 0x0B;
     const AUTHENTICATOR_LARGE_BLOBS: u8 = 0x0C;
@@ -123,6 +125,12 @@ impl Command {
                 // Parameters are ignored.
                 Ok(Command::AuthenticatorSelection)
             }
+            Command::AUTHENTICATOR_LARGE_BLOBS => {
+                let decoded_cbor = cbor::read(&bytes[1..])?;
+                Ok(Command::AuthenticatorLargeBlobs(
+                    AuthenticatorLargeBlobsParameters::try_from(decoded_cbor)?,
+                ))
+            }
             Command::AUTHENTICATOR_CONFIG => {
                 let decoded_cbor = cbor::read(&bytes[1..])?;
                 Ok(Command::AuthenticatorConfig(
@@ -351,6 +359,81 @@ impl TryFrom<cbor::Value> for AuthenticatorClientPinParameters {
     }
 }
 
+#[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug, PartialEq))]
+pub struct AuthenticatorLargeBlobsParameters {
+    pub get: Option<usize>,
+    pub set: Option<Vec<u8>>,
+    pub offset: usize,
+    pub length: Option<usize>,
+    pub pin_uv_auth_param: Option<Vec<u8>>,
+    pub pin_uv_auth_protocol: Option<u64>,
+}
+
+impl TryFrom<cbor::Value> for AuthenticatorLargeBlobsParameters {
+    type Error = Ctap2StatusCode;
+
+    fn try_from(cbor_value: cbor::Value) -> Result<Self, Ctap2StatusCode> {
+        destructure_cbor_map! {
+            let {
+                1 => get,
+                2 => set,
+                3 => offset,
+                4 => length,
+                5 => pin_uv_auth_param,
+                6 => pin_uv_auth_protocol,
+            } = extract_map(cbor_value)?;
+        }
+
+        // careful: some missing parameters here are CTAP1_ERR_INVALID_PARAMETER
+        let get = get.map(extract_unsigned).transpose()?.map(|u| u as usize);
+        let set = set.map(extract_byte_string).transpose()?;
+        let offset =
+            extract_unsigned(offset.ok_or(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)?)? as usize;
+        let length = length
+            .map(extract_unsigned)
+            .transpose()?
+            .map(|u| u as usize);
+        let pin_uv_auth_param = pin_uv_auth_param.map(extract_byte_string).transpose()?;
+        let pin_uv_auth_protocol = pin_uv_auth_protocol.map(extract_unsigned).transpose()?;
+
+        if get.is_none() && set.is_none() {
+            return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
+        }
+        if get.is_some() && set.is_some() {
+            return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
+        }
+        if get.is_some()
+            && (length.is_some() || pin_uv_auth_param.is_some() || pin_uv_auth_protocol.is_some())
+        {
+            return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
+        }
+        if set.is_some() && offset == 0 {
+            match length {
+                None => return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER),
+                Some(len) if len > MAX_LARGE_BLOB_ARRAY_SIZE => {
+                    return Err(Ctap2StatusCode::CTAP2_ERR_LARGE_BLOB_STORAGE_FULL)
+                }
+                Some(len) if len < MIN_LARGE_BLOB_LEN => {
+                    return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+                }
+                Some(_) => (),
+            }
+        }
+        if set.is_some() && offset != 0 && length.is_some() {
+            return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
+        }
+
+        Ok(AuthenticatorLargeBlobsParameters {
+            get,
+            set,
+            offset,
+            length,
+            pin_uv_auth_param,
+            pin_uv_auth_protocol,
+        })
+    }
+}
+
 #[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug, PartialEq))]
 pub struct AuthenticatorConfigParameters {
     pub sub_command: ConfigSubCommand,
@@ -698,6 +781,149 @@ mod test {
         assert_eq!(command, Ok(Command::AuthenticatorSelection));
     }
 
+    #[test]
+    fn test_from_cbor_large_blobs_parameters() {
+        // successful get
+        let cbor_value = cbor_map! {
+            1 => 2,
+            3 => 4,
+        };
+        let returned_large_blobs_parameters =
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value).unwrap();
+        let expected_large_blobs_parameters = AuthenticatorLargeBlobsParameters {
+            get: Some(2),
+            set: None,
+            offset: 4,
+            length: None,
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        assert_eq!(
+            returned_large_blobs_parameters,
+            expected_large_blobs_parameters
+        );
+
+        // successful first set
+        let cbor_value = cbor_map! {
+            2 => vec! [0x5E],
+            3 => 0,
+            4 => MIN_LARGE_BLOB_LEN as u64,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        let returned_large_blobs_parameters =
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value).unwrap();
+        let expected_large_blobs_parameters = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(vec![0x5E]),
+            offset: 0,
+            length: Some(MIN_LARGE_BLOB_LEN),
+            pin_uv_auth_param: Some(vec![0xA9]),
+            pin_uv_auth_protocol: Some(1),
+        };
+        assert_eq!(
+            returned_large_blobs_parameters,
+            expected_large_blobs_parameters
+        );
+
+        // successful next set
+        let cbor_value = cbor_map! {
+            2 => vec! [0x5E],
+            3 => 1,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        let returned_large_blobs_parameters =
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value).unwrap();
+        let expected_large_blobs_parameters = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(vec![0x5E]),
+            offset: 1,
+            length: None,
+            pin_uv_auth_param: Some(vec![0xA9]),
+            pin_uv_auth_protocol: Some(1),
+        };
+        assert_eq!(
+            returned_large_blobs_parameters,
+            expected_large_blobs_parameters
+        );
+
+        // failing with neither get nor set
+        let cbor_value = cbor_map! {
+            3 => 4,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        assert_eq!(
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value),
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+        );
+
+        // failing with get and set
+        let cbor_value = cbor_map! {
+            1 => 2,
+            2 => vec! [0x5E],
+            3 => 4,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        assert_eq!(
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value),
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+        );
+
+        // failing with get and length
+        let cbor_value = cbor_map! {
+            1 => 2,
+            3 => 4,
+            4 => MIN_LARGE_BLOB_LEN as u64,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        assert_eq!(
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value),
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+        );
+
+        // failing with zero offset and no length present
+        let cbor_value = cbor_map! {
+            2 => vec! [0x5E],
+            3 => 0,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        assert_eq!(
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value),
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+        );
+
+        // failing with length smaller than minimum
+        let cbor_value = cbor_map! {
+            2 => vec! [0x5E],
+            3 => 0,
+            4 => MIN_LARGE_BLOB_LEN as u64 - 1,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        assert_eq!(
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value),
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+        );
+
+        // failing with non-zero offset and length present
+        let cbor_value = cbor_map! {
+            2 => vec! [0x5E],
+            3 => 4,
+            4 => MIN_LARGE_BLOB_LEN as u64,
+            5 => vec! [0xA9],
+            6 => 1,
+        };
+        assert_eq!(
+            AuthenticatorLargeBlobsParameters::try_from(cbor_value),
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+        );
+    }
+
     #[test]
     fn test_vendor_configure() {
         // Incomplete command

src/ctap/credential_management.rs

@@ -100,7 +100,7 @@ fn enumerate_credentials_response(
         public_key: Some(public_key),
         total_credentials,
         cred_protect: cred_protect_policy,
-        // TODO(kaczmarczyck) add when largeBlobKey is implemented
+        // TODO(kaczmarczyck) add when largeBlobKey extension is implemented
         large_blob_key: None,
         ..Default::default()
     })

src/ctap/large_blobs.rs

@@ -0,0 +1,422 @@
+// Copyright 2020-2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::check_pin_uv_auth_protocol;
+use super::command::AuthenticatorLargeBlobsParameters;
+use super::pin_protocol_v1::{PinPermission, PinProtocolV1};
+use super::response::{AuthenticatorLargeBlobsResponse, ResponseData};
+use super::status_code::Ctap2StatusCode;
+use super::storage::PersistentStore;
+use alloc::vec;
+use alloc::vec::Vec;
+use byteorder::{ByteOrder, LittleEndian};
+use crypto::sha256::Sha256;
+use crypto::Hash256;
+
+/// This is maximum message size supported by the authenticator. 1024 is the default.
+/// Increasing this values can speed up commands with longer responses, but lead to
+/// packets dropping or unexpected failures.
+pub const MAX_MSG_SIZE: usize = 1024;
+/// The length of the truncated hash that as appended to the large blob data.
+const TRUNCATED_HASH_LEN: usize = 16;
+
+pub struct LargeBlobs {
+    buffer: Vec<u8>,
+    expected_length: usize,
+    expected_next_offset: usize,
+}
+
+/// Implements the logic for the AuthenticatorLargeBlobs command and keeps its state.
+impl LargeBlobs {
+    pub fn new() -> LargeBlobs {
+        LargeBlobs {
+            buffer: Vec::new(),
+            expected_length: 0,
+            expected_next_offset: 0,
+        }
+    }
+
+    /// Process the large blob command.
+    pub fn process_command(
+        &mut self,
+        persistent_store: &mut PersistentStore,
+        pin_protocol_v1: &mut PinProtocolV1,
+        large_blobs_params: AuthenticatorLargeBlobsParameters,
+    ) -> Result<ResponseData, Ctap2StatusCode> {
+        let AuthenticatorLargeBlobsParameters {
+            get,
+            set,
+            offset,
+            length,
+            pin_uv_auth_param,
+            pin_uv_auth_protocol,
+        } = large_blobs_params;
+
+        const MAX_FRAGMENT_LENGTH: usize = MAX_MSG_SIZE - 64;
+
+        if let Some(get) = get {
+            if get > MAX_FRAGMENT_LENGTH {
+                return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_LENGTH);
+            }
+            let config = persistent_store.get_large_blob_array(offset, get)?;
+            return Ok(ResponseData::AuthenticatorLargeBlobs(Some(
+                AuthenticatorLargeBlobsResponse { config },
+            )));
+        }
+
+        if let Some(mut set) = set {
+            if set.len() > MAX_FRAGMENT_LENGTH {
+                return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_LENGTH);
+            }
+            if offset == 0 {
+                // Checks for offset and length are already done in command.
+                self.expected_length =
+                    length.ok_or(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)?;
+                self.expected_next_offset = 0;
+            }
+            if offset != self.expected_next_offset {
+                return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_SEQ);
+            }
+            if persistent_store.pin_hash()?.is_some() {
+                let pin_uv_auth_param =
+                    pin_uv_auth_param.ok_or(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED)?;
+                // TODO(kaczmarczyck) Error codes for PIN protocol differ across commands.
+                // Change to Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED for None?
+                check_pin_uv_auth_protocol(pin_uv_auth_protocol)?;
+                pin_protocol_v1.has_permission(PinPermission::LargeBlobWrite)?;
+                let mut message = vec![0xFF; 32];
+                message.extend(&[0x0C, 0x00]);
+                let mut offset_bytes = [0u8; 4];
+                LittleEndian::write_u32(&mut offset_bytes, offset as u32);
+                message.extend(&offset_bytes);
+                message.extend(&Sha256::hash(set.as_slice()));
+                if !pin_protocol_v1.verify_pin_auth_token(&message, &pin_uv_auth_param) {
+                    return Err(Ctap2StatusCode::CTAP2_ERR_PIN_AUTH_INVALID);
+                }
+            }
+            if offset + set.len() > self.expected_length {
+                return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
+            }
+            if offset == 0 {
+                self.buffer = Vec::with_capacity(self.expected_length);
+            }
+            self.buffer.append(&mut set);
+            self.expected_next_offset = self.buffer.len();
+            if self.expected_next_offset == self.expected_length {
+                self.expected_length = 0;
+                self.expected_next_offset = 0;
+                // Must be a positive number.
+                let buffer_hash_index = self.buffer.len() - TRUNCATED_HASH_LEN;
+                if Sha256::hash(&self.buffer[..buffer_hash_index])[..TRUNCATED_HASH_LEN]
+                    != self.buffer[buffer_hash_index..]
+                {
+                    self.buffer = Vec::new();
+                    return Err(Ctap2StatusCode::CTAP2_ERR_INTEGRITY_FAILURE);
+                }
+                persistent_store.commit_large_blob_array(&self.buffer)?;
+                self.buffer = Vec::new();
+            }
+            return Ok(ResponseData::AuthenticatorLargeBlobs(None));
+        }
+
+        // This should be unreachable, since the command has either get or set.
+        Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crypto::rng256::ThreadRng256;
+
+    #[test]
+    fn test_process_command_get_empty() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+        let mut large_blobs = LargeBlobs::new();
+
+        let large_blob = vec![
+            0x80, 0x76, 0xBE, 0x8B, 0x52, 0x8D, 0x00, 0x75, 0xF7, 0xAA, 0xE9, 0x8D, 0x6F, 0xA5,
+            0x7A, 0x6D, 0x3C,
+        ];
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: Some(large_blob.len()),
+            set: None,
+            offset: 0,
+            length: None,
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        match large_blobs_response.unwrap() {
+            ResponseData::AuthenticatorLargeBlobs(Some(response)) => {
+                assert_eq!(response.config, large_blob);
+            }
+            _ => panic!("Invalid response type"),
+        };
+    }
+
+    #[test]
+    fn test_process_command_commit_and_get() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+        let mut large_blobs = LargeBlobs::new();
+
+        const BLOB_LEN: usize = 200;
+        const DATA_LEN: usize = BLOB_LEN - TRUNCATED_HASH_LEN;
+        let mut large_blob = vec![0x1B; DATA_LEN];
+        large_blob.extend_from_slice(&Sha256::hash(&large_blob[..])[..TRUNCATED_HASH_LEN]);
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob[..BLOB_LEN / 2].to_vec()),
+            offset: 0,
+            length: Some(BLOB_LEN),
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Ok(ResponseData::AuthenticatorLargeBlobs(None))
+        );
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob[BLOB_LEN / 2..].to_vec()),
+            offset: BLOB_LEN / 2,
+            length: None,
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Ok(ResponseData::AuthenticatorLargeBlobs(None))
+        );
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: Some(BLOB_LEN),
+            set: None,
+            offset: 0,
+            length: None,
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        match large_blobs_response.unwrap() {
+            ResponseData::AuthenticatorLargeBlobs(Some(response)) => {
+                assert_eq!(response.config, large_blob);
+            }
+            _ => panic!("Invalid response type"),
+        };
+    }
+
+    #[test]
+    fn test_process_command_commit_unexpected_offset() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+        let mut large_blobs = LargeBlobs::new();
+
+        const BLOB_LEN: usize = 200;
+        const DATA_LEN: usize = BLOB_LEN - TRUNCATED_HASH_LEN;
+        let mut large_blob = vec![0x1B; DATA_LEN];
+        large_blob.extend_from_slice(&Sha256::hash(&large_blob[..])[..TRUNCATED_HASH_LEN]);
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob[..BLOB_LEN / 2].to_vec()),
+            offset: 0,
+            length: Some(BLOB_LEN),
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Ok(ResponseData::AuthenticatorLargeBlobs(None))
+        );
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob[BLOB_LEN / 2..].to_vec()),
+            // The offset is 1 too big.
+            offset: BLOB_LEN / 2 + 1,
+            length: None,
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_SEQ),
+        );
+    }
+
+    #[test]
+    fn test_process_command_commit_unexpected_length() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+        let mut large_blobs = LargeBlobs::new();
+
+        const BLOB_LEN: usize = 200;
+        const DATA_LEN: usize = BLOB_LEN - TRUNCATED_HASH_LEN;
+        let mut large_blob = vec![0x1B; DATA_LEN];
+        large_blob.extend_from_slice(&Sha256::hash(&large_blob[..])[..TRUNCATED_HASH_LEN]);
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob[..BLOB_LEN / 2].to_vec()),
+            offset: 0,
+            // The length is 1 too small.
+            length: Some(BLOB_LEN - 1),
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Ok(ResponseData::AuthenticatorLargeBlobs(None))
+        );
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob[BLOB_LEN / 2..].to_vec()),
+            offset: BLOB_LEN / 2,
+            length: None,
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER),
+        );
+    }
+
+    #[test]
+    fn test_process_command_commit_unexpected_hash() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+        let mut large_blobs = LargeBlobs::new();
+
+        const BLOB_LEN: usize = 20;
+        // This blob does not have an appropriate hash.
+        let large_blob = vec![0x1B; BLOB_LEN];
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob.to_vec()),
+            offset: 0,
+            length: Some(BLOB_LEN),
+            pin_uv_auth_param: None,
+            pin_uv_auth_protocol: None,
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Err(Ctap2StatusCode::CTAP2_ERR_INTEGRITY_FAILURE),
+        );
+    }
+
+    #[test]
+    fn test_process_command_commit_with_pin() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+        let mut large_blobs = LargeBlobs::new();
+
+        const BLOB_LEN: usize = 20;
+        const DATA_LEN: usize = BLOB_LEN - TRUNCATED_HASH_LEN;
+        let mut large_blob = vec![0x1B; DATA_LEN];
+        large_blob.extend_from_slice(&Sha256::hash(&large_blob[..])[..TRUNCATED_HASH_LEN]);
+
+        persistent_store.set_pin(&[0u8; 16], 4).unwrap();
+        let pin_uv_auth_param = Some(vec![
+            0x68, 0x0C, 0x3F, 0x6A, 0x62, 0x47, 0xE6, 0x7C, 0x23, 0x1F, 0x79, 0xE3, 0xDC, 0x6D,
+            0xC3, 0xDE,
+        ]);
+
+        let large_blobs_params = AuthenticatorLargeBlobsParameters {
+            get: None,
+            set: Some(large_blob),
+            offset: 0,
+            length: Some(BLOB_LEN),
+            pin_uv_auth_param,
+            pin_uv_auth_protocol: Some(1),
+        };
+        let large_blobs_response = large_blobs.process_command(
+            &mut persistent_store,
+            &mut pin_protocol_v1,
+            large_blobs_params,
+        );
+        assert_eq!(
+            large_blobs_response,
+            Ok(ResponseData::AuthenticatorLargeBlobs(None))
+        );
+    }
+}

src/ctap/mod.rs

@@ -21,6 +21,7 @@ mod ctap1;
 pub mod data_formats;
 pub mod hid;
 mod key_material;
+mod large_blobs;
 mod pin_protocol_v1;
 pub mod response;
 pub mod status_code;
@@ -41,6 +42,7 @@ use self::data_formats::{
     SignatureAlgorithm,
 };
 use self::hid::ChannelID;
+use self::large_blobs::{LargeBlobs, MAX_MSG_SIZE};
 use self::pin_protocol_v1::{PinPermission, PinProtocolV1};
 use self::response::{
     AuthenticatorGetAssertionResponse, AuthenticatorGetInfoResponse,
@@ -293,6 +295,7 @@ pub struct CtapState<'a, R: Rng256, CheckUserPresence: Fn(ChannelID) -> Result<(
     pub u2f_up_state: U2fUserPresenceState,
     // The state initializes to Reset and its timeout, and never goes back to Reset.
     stateful_command_permission: StatefulPermission,
+    large_blobs: LargeBlobs,
 }
 
 impl<'a, R, CheckUserPresence> CtapState<'a, R, CheckUserPresence>
@@ -318,6 +321,7 @@ where
                 Duration::from_ms(TOUCH_TIMEOUT_MS),
             ),
             stateful_command_permission: StatefulPermission::new_reset(now),
+            large_blobs: LargeBlobs::new(),
         }
     }
 
@@ -484,12 +488,16 @@ where
                         )
                     }
                     Command::AuthenticatorSelection => self.process_selection(cid),
+                    Command::AuthenticatorLargeBlobs(params) => self.large_blobs.process_command(
+                        &mut self.persistent_store,
+                        &mut self.pin_protocol_v1,
+                        params,
+                    ),
                     Command::AuthenticatorConfig(params) => process_config(
                         &mut self.persistent_store,
                         &mut self.pin_protocol_v1,
                         params,
                     ),
-                    // TODO(kaczmarczyck) implement FIDO 2.1 commands
                     // Vendor specific commands
                     Command::AuthenticatorVendorConfigure(params) => {
                         self.process_vendor_configure(params, cid)
@@ -1026,7 +1034,7 @@ where
                 ]),
                 aaguid: self.persistent_store.aaguid()?,
                 options: Some(options_map),
-                max_msg_size: Some(1024),
+                max_msg_size: Some(MAX_MSG_SIZE as u64),
                 pin_protocols: Some(vec![PIN_PROTOCOL_VERSION]),
                 max_credential_count_in_list: MAX_CREDENTIAL_COUNT_IN_LIST.map(|c| c as u64),
                 max_credential_id_length: Some(CREDENTIAL_ID_SIZE as u64),
@@ -1259,7 +1267,7 @@ mod test {
                 "setMinPINLength" => true,
                 "forcePINChange" => false,
             },
-            0x05 => 1024,
+            0x05 => MAX_MSG_SIZE as u64,
             0x06 => cbor_array_vec![vec![1]],
             0x07 => MAX_CREDENTIAL_COUNT_IN_LIST.map(|c| c as u64),
             0x08 => CREDENTIAL_ID_SIZE as u64,

src/ctap/pin_protocol_v1.rs

@@ -162,7 +162,7 @@ pub enum PinPermission {
     GetAssertion = 0x02,
     CredentialManagement = 0x04,
     BioEnrollment = 0x08,
-    PlatformConfiguration = 0x10,
+    LargeBlobWrite = 0x10,
     AuthenticatorConfiguration = 0x20,
 }
 

src/ctap/response.rs

@@ -33,6 +33,7 @@ pub enum ResponseData {
     AuthenticatorReset,
     AuthenticatorCredentialManagement(Option<AuthenticatorCredentialManagementResponse>),
     AuthenticatorSelection,
+    AuthenticatorLargeBlobs(Option<AuthenticatorLargeBlobsResponse>),
     // TODO(kaczmarczyck) dummy, extend
     AuthenticatorConfig,
     AuthenticatorVendor(AuthenticatorVendorResponse),
@@ -49,6 +50,7 @@ impl From<ResponseData> for Option<cbor::Value> {
             ResponseData::AuthenticatorReset => None,
             ResponseData::AuthenticatorCredentialManagement(data) => data.map(|d| d.into()),
             ResponseData::AuthenticatorSelection => None,
+            ResponseData::AuthenticatorLargeBlobs(data) => data.map(|d| d.into()),
             ResponseData::AuthenticatorConfig => None,
             ResponseData::AuthenticatorVendor(data) => Some(data.into()),
         }
@@ -204,6 +206,22 @@ impl From<AuthenticatorClientPinResponse> for cbor::Value {
     }
 }
 
+#[cfg_attr(test, derive(PartialEq))]
+#[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug))]
+pub struct AuthenticatorLargeBlobsResponse {
+    pub config: Vec<u8>,
+}
+
+impl From<AuthenticatorLargeBlobsResponse> for cbor::Value {
+    fn from(platform_large_blobs_response: AuthenticatorLargeBlobsResponse) -> Self {
+        let AuthenticatorLargeBlobsResponse { config } = platform_large_blobs_response;
+
+        cbor_map_options! {
+            0x01 => config,
+        }
+    }
+}
+
 #[derive(Default)]
 #[cfg_attr(test, derive(PartialEq))]
 #[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug))]
@@ -510,6 +528,23 @@ mod test {
         assert_eq!(response_cbor, None);
     }
 
+    #[test]
+    fn test_large_blobs_into_cbor() {
+        let large_blobs_response = AuthenticatorLargeBlobsResponse { config: vec![0xC0] };
+        let response_cbor: Option<cbor::Value> =
+            ResponseData::AuthenticatorLargeBlobs(Some(large_blobs_response)).into();
+        let expected_cbor = cbor_map_options! {
+            0x01 => vec![0xC0],
+        };
+        assert_eq!(response_cbor, Some(expected_cbor));
+    }
+
+    #[test]
+    fn test_empty_large_blobs_into_cbor() {
+        let response_cbor: Option<cbor::Value> = ResponseData::AuthenticatorLargeBlobs(None).into();
+        assert_eq!(response_cbor, None);
+    }
+
     #[test]
     fn test_config_into_cbor() {
         let response_cbor: Option<cbor::Value> = ResponseData::AuthenticatorConfig.into();

src/ctap/storage.rs

@@ -28,9 +28,10 @@ use alloc::vec;
 use alloc::vec::Vec;
 use arrayref::array_ref;
 use cbor::cbor_array_vec;
+use core::cmp;
 use core::convert::TryInto;
 use crypto::rng256::Rng256;
-use persistent_store::StoreUpdate;
+use persistent_store::{fragment, StoreUpdate};
 
 // Those constants may be modified before compilation to tune the behavior of the key.
 //
@@ -59,6 +60,7 @@ const DEFAULT_MIN_PIN_LENGTH_RP_IDS: Vec<String> = Vec::new();
 // This constant is an attempt to limit storage requirements. If you don't set it to 0,
 // the stored strings can still be unbounded, but that is true for all RP IDs.
 pub const MAX_RP_IDS_LENGTH: usize = 8;
+pub const MAX_LARGE_BLOB_ARRAY_SIZE: usize = 2048;
 
 /// Wrapper for master keys.
 pub struct MasterKeys {
@@ -467,6 +469,51 @@ impl PersistentStore {
         )?)
     }
 
+    /// Reads the byte vector stored as the serialized large blobs array.
+    ///
+    /// If too few bytes exist at that offset, return the maximum number
+    /// available. This includes cases of offset being beyond the stored array.
+    ///
+    /// If no large blob is committed to the store, get responds as if an empty
+    /// CBOR array (0x80) was written, together with the 16 byte prefix of its
+    /// SHA256, to a total length of 17 byte (which is the shortest legitimate
+    /// large blob entry possible).
+    pub fn get_large_blob_array(
+        &self,
+        offset: usize,
+        byte_count: usize,
+    ) -> Result<Vec<u8>, Ctap2StatusCode> {
+        let byte_range = offset..offset + byte_count;
+        let output = fragment::read_range(&self.store, &key::LARGE_BLOB_SHARDS, byte_range)?;
+        Ok(output.unwrap_or_else(|| {
+            const EMPTY_LARGE_BLOB: [u8; 17] = [
+                0x80, 0x76, 0xBE, 0x8B, 0x52, 0x8D, 0x00, 0x75, 0xF7, 0xAA, 0xE9, 0x8D, 0x6F, 0xA5,
+                0x7A, 0x6D, 0x3C,
+            ];
+            let last_index = cmp::min(EMPTY_LARGE_BLOB.len(), offset + byte_count);
+            EMPTY_LARGE_BLOB
+                .get(offset..last_index)
+                .unwrap_or_default()
+                .to_vec()
+        }))
+    }
+
+    /// Sets a byte vector as the serialized large blobs array.
+    pub fn commit_large_blob_array(
+        &mut self,
+        large_blob_array: &[u8],
+    ) -> Result<(), Ctap2StatusCode> {
+        // This input should have been caught at caller level.
+        if large_blob_array.len() > MAX_LARGE_BLOB_ARRAY_SIZE {
+            return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
+        }
+        Ok(fragment::write(
+            &mut self.store,
+            &key::LARGE_BLOB_SHARDS,
+            large_blob_array,
+        )?)
+    }
+
     /// Returns the attestation private key if defined.
     pub fn attestation_private_key(
         &self,
@@ -1144,6 +1191,86 @@ mod test {
         assert_eq!(persistent_store.min_pin_length_rp_ids().unwrap(), rp_ids);
     }
 
+    #[test]
+    fn test_max_large_blob_array_size() {
+        let mut rng = ThreadRng256 {};
+        let persistent_store = PersistentStore::new(&mut rng);
+
+        #[allow(clippy::assertions_on_constants)]
+        {
+            assert!(MAX_LARGE_BLOB_ARRAY_SIZE >= 1024);
+        }
+        assert!(
+            MAX_LARGE_BLOB_ARRAY_SIZE
+                <= persistent_store.store.max_value_length()
+                    * (key::LARGE_BLOB_SHARDS.end - key::LARGE_BLOB_SHARDS.start)
+        );
+    }
+
+    #[test]
+    fn test_commit_get_large_blob_array() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+
+        let large_blob_array = vec![0x01, 0x02, 0x03];
+        assert!(persistent_store
+            .commit_large_blob_array(&large_blob_array)
+            .is_ok());
+        let restored_large_blob_array = persistent_store.get_large_blob_array(0, 1).unwrap();
+        assert_eq!(vec![0x01], restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(1, 1).unwrap();
+        assert_eq!(vec![0x02], restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(2, 1).unwrap();
+        assert_eq!(vec![0x03], restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(2, 2).unwrap();
+        assert_eq!(vec![0x03], restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(3, 1).unwrap();
+        assert_eq!(Vec::<u8>::new(), restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(4, 1).unwrap();
+        assert_eq!(Vec::<u8>::new(), restored_large_blob_array);
+    }
+
+    #[test]
+    fn test_commit_get_large_blob_array_overwrite() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+
+        let large_blob_array = vec![0x11; 5];
+        assert!(persistent_store
+            .commit_large_blob_array(&large_blob_array)
+            .is_ok());
+        let large_blob_array = vec![0x22; 4];
+        assert!(persistent_store
+            .commit_large_blob_array(&large_blob_array)
+            .is_ok());
+        let restored_large_blob_array = persistent_store.get_large_blob_array(0, 5).unwrap();
+        assert_eq!(large_blob_array, restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(4, 1).unwrap();
+        assert_eq!(Vec::<u8>::new(), restored_large_blob_array);
+
+        assert!(persistent_store.commit_large_blob_array(&[]).is_ok());
+        let restored_large_blob_array = persistent_store.get_large_blob_array(0, 20).unwrap();
+        // Committing an empty array resets to the default blob of 17 byte.
+        assert_eq!(restored_large_blob_array.len(), 17);
+    }
+
+    #[test]
+    fn test_commit_get_large_blob_array_no_commit() {
+        let mut rng = ThreadRng256 {};
+        let persistent_store = PersistentStore::new(&mut rng);
+
+        let empty_blob_array = vec![
+            0x80, 0x76, 0xBE, 0x8B, 0x52, 0x8D, 0x00, 0x75, 0xF7, 0xAA, 0xE9, 0x8D, 0x6F, 0xA5,
+            0x7A, 0x6D, 0x3C,
+        ];
+        let restored_large_blob_array = persistent_store.get_large_blob_array(0, 17).unwrap();
+        assert_eq!(empty_blob_array, restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(0, 1).unwrap();
+        assert_eq!(vec![0x80], restored_large_blob_array);
+        let restored_large_blob_array = persistent_store.get_large_blob_array(16, 1).unwrap();
+        assert_eq!(vec![0x3C], restored_large_blob_array);
+    }
+
     #[test]
     fn test_global_signature_counter() {
         let mut rng = ThreadRng256 {};

src/ctap/storage/key.rs

@@ -88,6 +88,11 @@ make_partition! {
     /// board may configure `MAX_SUPPORTED_RESIDENT_KEYS` depending on the storage size.
     CREDENTIALS = 1700..2000;
 
+    /// Storage for the serialized large blob array.
+    ///
+    /// The stored large blob can be too big for one key, so it has to be sharded.
+    LARGE_BLOB_SHARDS = 2000..2004;
+
     /// If this entry exists and equals 1, the PIN needs to be changed.
     FORCE_PIN_CHANGE = 2040;